includes/filebackend/lockmanager/ScopedLock.php

   1 <?php
   2 /**
   3  * Resource locking handling.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  * @ingroup LockManager
  22  * @author Aaron Schulz
  23  */
  24
  25 /**
  26  * Self-releasing locks
  27  *
  28  * LockManager helper class to handle scoped locks, which
  29  * release when an object is destroyed or goes out of scope.
  30  *
  31  * @ingroup LockManager
  32  * @since 1.19
  33  */
  34 class ScopedLock {
  35         /** @var LockManager */
  36         protected $manager;
  37         /** @var Status */
  38         protected $status;
  39         /** @var Array Map of lock types to resource paths */
  40         protected $pathsByType;
  41
  42         /**
  43          * @param LockManager $manager
  44          * @param array $pathsByType Map of lock types to path lists
  45          * @param Status $status
  46          */
  47         protected function __construct( LockManager $manager, array $pathsByType, Status $status ) {
  48                 $this->manager = $manager;
  49                 $this->pathsByType = $pathsByType;
  50                 $this->status = $status;
  51         }
  52
  53         /**
  54          * Get a ScopedLock object representing a lock on resource paths.
  55          * Any locks are released once this object goes out of scope.
  56          * The status object is updated with any errors or warnings.
  57          *
  58          * $type can be "mixed" and $paths can be a map of types to paths (since 1.22).
  59          * Otherwise $type should be an integer and $paths should be a list of paths.
  60          *
  61          * @param LockManager $manager
  62          * @param array $paths List of storage paths or map of lock types to path lists
  63          * @param integer|string $type LockManager::LOCK_* constant or "mixed"
  64          * @param Status $status
  65          * @param integer $timeout Timeout in seconds (0 means non-blocking) (since 1.22)
  66          * @return ScopedLock|null Returns null on failure
  67          */
  68         public static function factory(
  69                 LockManager $manager, array $paths, $type, Status $status, $timeout = 0
  70         ) {
  71                 $pathsByType = is_integer( $type ) ? array( $type => $paths ) : $paths;
  72                 $lockStatus = $manager->lockByType( $pathsByType, $timeout );
  73                 $status->merge( $lockStatus );
  74                 if ( $lockStatus->isOK() ) {
  75                         return new self( $manager, $pathsByType, $status );
  76                 }
  77
  78                 return null;
  79         }
  80
  81         /**
  82          * Release a scoped lock and set any errors in the attatched Status object.
  83          * This is useful for early release of locks before function scope is destroyed.
  84          * This is the same as setting the lock object to null.
  85          *
  86          * @param ScopedLock $lock
  87          * @return void
  88          * @since 1.21
  89          */
  90         public static function release( ScopedLock &$lock = null ) {
  91                 $lock = null;
  92         }
  93
  94         /**
  95          * Release the locks when this goes out of scope
  96          */
  97         function __destruct() {
  98                 $wasOk = $this->status->isOK();
  99                 $this->status->merge( $this->manager->unlockByType( $this->pathsByType ) );
 100                 if ( $wasOk ) {
 101                         // Make sure status is OK, despite any unlockFiles() fatals
 102                         $this->status->setResult( true, $this->status->value );
 103                 }
 104         }
 105 }